In recent years, a technique of forming a thin film transistor (TFT) using a semiconductor thin film (with a thickness of approximately from several nm to several hundreds nm), which is formed over a substrate with an insulated surface, has been attracting attention. The thin film transistor has been widely applied in various electronic devices such as an IC and an electronic apparatus. In particular, development related to the thin film transistor as a switching element for a liquid crystal display device or a light emitting display device has been carried out hurriedly.
In a liquid crystal display device, a liquid crystal material is sandwiched between an element substrate and an opposing substrate having an opposing electrode that is positioned opposite to the element substrate. On the element substrate, TFTs using amorphous silicon or polysilicon as their semiconductors are arranged in matrix, and pixel electrodes, source wirings, and gate wirings each of which connects to each TFT are formed, respectively. A color filter for color display is formed either on the element substrate or the opposing substrate. Polarizing plates are arranged on the element substrate and the opposing substrate as optical shutters, respectively, to display color images.
The color filter of the liquid crystal display device includes colored layers consisting of R (red), G (green), B (blue), and a light shielding mask (a black matrix) for covering gaps between pixels, and extracts red, green, and blue lights by transmitting light therethrough. A light shielding mask for the color filter is generally made from a metal film or an organic film containing a black pigment. The color filter is arranged at a position corresponding to the pixels, thereby being capable of changing the colors of light to be extracted for each pixel. Note that, the position corresponding to the pixels indicates a position that accords with a pixel electrode.
In a light emitting display device, there are a colorizing method by arranging light emitting elements that emit red, green, and blue lights, respectively, in matrix; a colorizing method by utilizing a color filter with use of a light emitting element that emits white light; and the like. The colorizing method by utilizing the color filter with use of the light emitting element that emits white light is similar to a colorizing method for a liquid crystal display device using a color filter, in principle (see patent document 1).
Further, with respect to the light emitting display device, there is a light emitting device in which a color filter is provided on a side of an element substrate (see patent document 2).    [Patent document 1]: Japanese Patent Application Laid-Open No. 2001-217072    [Patent document 2]: Japanese Patent Application Laid-Open No. 2002-15861